Hi Bernard, here are the reasons why the cooling blocks of M825 and M925 look the way they do....
* The semi-enclosed Venturi chimneys of these cooling units are more efficient than traditional blade designs in accellerating upwards air-flow and dissipating heat.
* The Venturi chimney design was first introduced in the M10 and M12 amps, and then re-introduced and finalized in the M625, with the prismatic faceplate first introduced in mid-production M312. Since M625, higher end Rowland amps have maintained the same consistent design.
* M825 generates more heat than you might imagine... Only NCore modules in M825 operate in class D, and by themselves generate more heat than old ICEpower modules used in old M3xx series... And there are two NCore modules inside M825. The rest of the circuit does generate larger amounts of heat than the power conversion modules, particularly in the power supply unit, where the SMPS and the PFC unit are quite massive... My music loft reacheas a normal temperature of 86F under air conditioning during summer months: in this season, the Venturi chimneys are a real blessing, because the unit becomes uniformly toasty to the touch... The uniform heat distribution ensures that internal components do not overheat, and so long term reliability is maximized.
* Of course, the total designs does contribute to pride of ownership... Doesn't it *grins!*
G